This is a single-phase jet, e.g. liquid-liquid or gas-gas jet; correspondingly, we should have \(\rho _e=\rho _0\) . This case corresponds to \(\rho _*=1\)  in dimensionless form. From Eq. (REF ) we have that \(\rho =\rho _0(\equiv \rho _e)\) , as expected so the density is just that of the common fluid for all distances. [1]} called this a “submerged jet” while [2]} called it a “point source of momentum jet”.
